Digital Logic Design MScIT 1st Term Past paper 2014 UOS

Posted by Ayesha

University of Sargodha
M.Sc. I.T, First Term Exam 2014
Subject: Information Technology
Paper: Logic Design & Computer Organization (CMP: 523)
Time Allowed: 2:30 Hour
Maximum Marks: 80

Objective Part

Q.1. Write short answers of the following on your answer sheet. (2×16)

i. Show 7000 in weighted code 5043210.
ii. In what conditions Tabulation method is better than Boolean Algebra.
iii. Convert the following binary numbers: i) 1110 ii) 0111 to Gray codes.
iv. Simplify to minimum number of literals: (x + ȳ)(x + y)
v. Find 2’s complement, where most significant bit is a sign bit (1011110101)₂.
vi. Draw the gate implementation using AND, OR, NOT gates of the function:
A · (B + C) · (A + E)
vii. Obtain expression in POS: F(A, B, C, D) = ∏(0, 1, 2, 3, 4, 6, 8, 11, 12, 15).
viii. Prove (x + y)² = x + y by truth table.
ix. Draw diagram of SR-Latch using NAND-gates.
x. Simplify the expression: y = A B̅ D + A B̅ D̅
xi. Convert (6203)₁₀ into hexadecimal number.
xii. Give brief description of negative-AND gate.
xiii. Implement half adder with logic diagram.
xiv. Convert (1225)₁₀ into Octal.
xv. Explain how an Exclusive-NOR gate can be used to compare two binary bits?
xvi. State and provide basic concept of Multiplexer.

Subjective Part (4×12)

Q.2. What is Demultiplexer? Explain with 2-to-4 lines Decoder with enable (E) input & define its truth table and block diagram.

Q.3. Implement the block diagram of Boolean function:
F = A(B̅ + C̅D̅) + B̅C̅ + AC using universal NAND gates.

Q.4. What is K Map? Simplify the following Boolean function by using this method and also draw logic diagram.
F(A,B,C,D) = ∑ (0, 1, 2, 4, 6, 8, 9,10, 11, 14, 15)
D(A,B,C,D) = ∑ (3,5,13)

Q.5. Code conversion of BCD to 2 4 2 1 and draw a logic diagram.

Q.6. What is Full Subtractor? Define the truth table to map the Full subtractor & implement with two half subtractor and OR gate.

Q.7. Draw the truth table and logic diagram to explain basic operation of Edge triggered T-Flip Flop. Also explain the toggle states characteristics.